Dual layer heat shrink tubing

Abstract

The present disclosure provides a dual layer heat shrink tube having: an inner polymeric layer with a thickness t 1 and an outer diameter D 1 ; and an outer, expanded polymeric layer with a thickness t 2 ′ and an outer diameter D 2 ′ obtained by expanding a polymer tube from D 2 to D 2 ′ and t 2 to t 2 ′ at a selected temperature so that D 2 ′- 2 (t 2 ′)>D 1 , wherein a ring cut from a cross-section of the dual layer heat shrink tube, slit into a rectangle and gripped at cut ends by tension grips within a DMA, and subjected to a temperature sweep of 3° C./min at a frequency of 1 Hz from the onset of a melting endotherm of the inner polymeric layer to that of the outer, expanded polymeric layer is greater than 1° C. and less than 12° C. The disclosure further provides associated methods for preparing and using such tubes, as well as to products comprising such tubes.

1 .- 24 . (canceled) 
     
     
         25 . A dual layer heat shrink tube comprising:
 an inner polymeric layer consisting essentially of PFA, FEP, EFEP, or PVDF and, optionally, one or more pigments, dyes, or fillers, and   an outer expanded polymeric layer consisting essentially of PTFE, FEP, PFA, PEEK, or PVDF,   wherein the dual layer heat shrink tube exhibits an area under a tan δ curve that is greater than 1° C. and less than 12° C. as determined by a Dynamic Mechanical Analyzer (DMA).   
     
     
         26 . The dual layer heat shrink tube of  claim 25 , wherein the outer expanded polymeric layer consists essentially of PTFE and the inner polymeric layer consists essentially of PFA. 
     
     
         27 . The dual layer heat shrink tube of  claim 25 , wherein the outer expanded polymeric layer consists essentially of PTFE and the inner polymeric layer consists essentially of FEP. 
     
     
         28 . The dual layer heat shrink tube of  claim 25 , wherein the outer expanded polymeric layer consists essentially of PFA and the inner polymeric layer consists essentially of FEP. 
     
     
         29 . The dual layer heat shrink tube of  claim 25 , wherein the outer expanded polymeric layer consists essentially of PEEK and the inner polymeric layer consists essentially of FEP. 
     
     
         30 . The dual layer heat shrink tube of  claim 25 , wherein the outer expanded polymeric layer consists essentially of FEP and the inner polymeric layer consists essentially of EFEP. 
     
     
         31 . The dual layer heat shrink tube of  claim 25 , wherein the outer expanded polymeric layer consists essentially of FEP and the inner polymeric layer consists essentially of PVDF. 
     
     
         32 . The dual layer heat shrink tube of  claim 25 , wherein the outer expanded polymeric layer is removable after being heat shrunk. 
     
     
         33 . The dual layer heat shrink tube of  claim 32 , wherein the outer, expanded polymeric layer is peelable after being heat shrunk. 
     
     
         34 . The dual layer heat shrink tube of  claim 25 , wherein the inner polymeric layer comprises a filler. 
     
     
         35 . The dual layer heat shrink tube of  claim 25 , wherein the inner polymeric layer is not an expanded polymeric layer. 
     
     
         36 . The dual layer heat shrink tube of  claim 25 , wherein the inner polymeric layer is not an oriented polymeric layer. 
     
     
         37 . A method of encapsulating a component, comprising: applying the dual layer heat shrink tube of  claim 25  around the component, heating the dual layer shrink tube, and cooling the resulting encapsulated component. 
     
     
         38 . The component of  claim 37 , wherein the component comprises a thermistor or a thermocouple. 
     
     
         39 . A method for evaluating the suitability of a dual layer heat shrink tube, comprising:
 providing a dual layer heat shrink tube comprising an inner polymeric layer and an outer expanded polymeric layer in the form of a polymer tube,   wherein the dual heat shrink tube exhibits an area under the tan delta curve between 1° C. and 12° C.,   wherein the area under the tan δ curve is determined by using a Dynamic Mechanical Analyzer (DMA).   
     
     
         40 . The method of  claim 39 , wherein the DMA uses a rate of 3° C. per minute at a frequency of 1 Hz from the onset of a melting endotherm of the inner polymeric layer up to the onset of a melting endotherm of the outer, expanded polymeric layer.